Synthesis of 6-(arylmethylidene)octahydropyrrolo[1,2-a]pyrimidines and 5-(arylmethylidene)hexahydropyrrolo[1,2-a]imidazoles by the interaction of alk-4-ynals with a,?-diaminoalkanes in DMSO in the presence of KOH

Cyclization of alk-4-ynals with a,?-diaminoalkanes in DMSO under the action of KOH affords bicyclic N,N-enaminals – 6-(aryl- methylidene)octahydro[1,2-a]pyrimidines and 5-(arylmethylidene)hexahydro[1,2-a]imidazoles.